Solar collector

ABSTRACT

A solar collector which comprises a mineral wool insulation based on man-made vitreous fibers (MMVF) which are bonded by a formaldehyde-free polymeric binder system. This Abstract is not intended to define the invention disclosed in the specification, nor intended to limit the scope of the invention in any way.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119 of EuropeanPatent Application No. 06017564.3, filed Aug. 23, 2006, and of U.S.Provisional Application No. 60/859,498, filed Nov. 17, 2006. Thedisclosures of these applications are expressly incorporated byreference herein in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a solar collector, in particular, aflat-plate collector, having a mineral wool insulation based on man-madevitreous fibers (MMVF) which are bonded by a formaldehyde-free polymericbinder system.

2. Discussion of Background Information

Solar collectors transform solar radiation into heat and transfer thatheat to a medium (water, solar fluid, or air). The solar heat can, forinstance, be used for heating water, to back up heating systems or forheating swimming pools.

Solar collectors can be classified into two major categories based onthe working fluid used to cool them. These two are “liquid” and “air”.Each of the two categories can then be sub-classified according toaverage temperature range over which they are intended to be used, andcan be used effectively. These classifications are: “low temperature”,“medium temperature” and “high temperature”, with some overlap among theclassifications depending on the construction of the individualcollector model.

Low-Temperature Collectors

Plastic low-temperature collectors have been used widely for swimmingpool heating. However, because of the deteriorating effects ofultraviolet radiation and stagnation temperatures on some plastic solarcollectors, metal collectors are being more widely utilized. Unglazedcollectors with aluminum absorber plates and copper water passagesappear to be most cost effective over the typical metal collector lifetime of 20 years or more. All-copper collectors for swimming poolheating also work well, but are generally more expensive for the sameperformance characteristics. Copper is preferred over any other metalfor water passages because of its high conductivity and compatibilitywith water. Almost all other metals must be separated from directcontact with the water being heated by a heat exchanger, which seriouslyreduces the collector efficiency.

Medium-Temperature Collectors

Medium temperature collectors typically are flat-plate collectors,enclosed in an insulated case, with one or two glazings. The intendedtemperature range of operation is from about 10° C. to 100° C. aboveambient temperature. For the lower end of this range, single-glazedcollectors with non-selective absorber plates are most cost effective.In the middle and high end of the range, selective collectors with oneor two glazings become more cost effective. Typical applications includewater heating, space heating and some medium temperature industrialheating uses.

High Temperature Collectors

High temperature collectors include some overlap from flat platecollectors in the medium temperature range, with selective absorberplates and heavy insulation, and may have temperature capabilitiesenhanced in installation by being mounted in a sun-tracking system. Manyother variations of high temperature collectors include evacuated-tubeflat plate types, parabolic dish reflector types, parabolic trough typesand modified parabola types. Most high temperature collectors depend onsome type of sun tracking, in one or two axes, for effective operation.Tracking collectors are used to a small extent for domestic waterheating and space heating, but are limited in cost effectiveness andreliability by the complexities of the tracking mechanisms, where used.Other uses are highly specialized, such as in absorption coolingsystems, and applications where steam must be generated, or very hightemperatures are required with sacrifice of efficiency. While parabolicand other types of focusing collectors do not respond to indirect solarradiation, and collect little, if any heat when the sun is obscuredenough to prevent a clear shadow from being thrown, flat platecollectors respond to radiation from all directions, and will collectdiffuse radiation energy of as much as 30% of normal direct energy whenthere is no visible shadow.

Flat Plate Collectors

The design of a typical flat-plate collector is illustrated in theattached FIGURE and consists essentially of an absorber, a transparentcover, a housing, and an insulation. A plurality of pipes or tubes maybe used for carrying a heat transfer medium. The flat plate collectorshown in the FIGURE is but one of many examples of suitable solarcollector designs, and the present invention is not limited to flatplate collectors or to the specific embodiment shown.

The heart of a solar collector is the absorber, which is usuallycomposed of several narrow metal strips. A carrier fluid for heattransfer flows through heat-carrying pipes or tubes, which are connectedto the absorber strip. In plate-type absorbers, two sheets aresandwiched together, allowing the medium to flow between the two sheets.Absorbers are typically made of copper or aluminum.

Swimming pool absorbers, on the other hand, are usually made of plastic(mostly EPDM, but also of polypropylene and polyethylene), as the lowertemperatures involved do not require greater heat capacity.

Usually low-iron solar safety glass is used as a transparent cover, asit transmits a great amount of the short-wave light spectrum.Simultaneously, only very little of the heat emitted by the absorberescapes the cover (greenhouse effect). In addition, the transparentcover prevents the collected heat of being carried away by wind orconvection. Together with the housing, the cover protects the absorberfrom adverse weather conditions. Typical housing (case) materialsinclude aluminum and galvanized steel; sometimes fiberglass-reinforcedplastic is used.

Case insulation is not the only important thermal insulation in aquality collector. The absorber plate and connecting tubing penetratingthe housing must be thermally insulated from the case at all points ofsupport. Heat losses can be severe if either the absorber or tubingtouches the case or is supported through heat-conducting materials tothe case.

As an insulation material, polyurethane or polyisocyanurate foam hasbecome popular for solar collectors because it has a high insulationvalue and is very easy to handle. However, its use is associated withcertain disadvantages. An otherwise well-designed solar collector willexperience stagnation temperatures of up to 260° C. that will cause theinsulation of this type to outgas and rapidly destroy the effectivenessof the collector by condensation of volatile organic components andformation of visible deposits on the transparent cover (so-called“fogging effect”). Furthermore, urethane and related products may beprohibited in collectors in fire hazard areas, because of their toxicfume production.

Similarly, insulating materials based on mineral fibers bonded withconventional phenol/formaldehyde resins have the disadvantage ofundesired toxic formaldehyde emission at the high working temperaturesof solar collectors, in particular, during stagnation periods.

Accordingly, there exists a need for improved insulating materials whichare suitable for use in solar collectors.

It would be desirable to have available a solar collector which has amineral wool insulation that avoids or at least reduces the detrimentaleffect of condensation or deposition of volatile binder components orbinder decomposition products (“fogging”) on performance and efficiencyof the solar collector.

It would also be desirable to have available a solar collector which hasan mineral wool insulation that is not associated with the healthhazards of prior art insulation materials.

SUMMARY OF THE INVENTION

The present invention provides a solar collector which has a mineralwool insulation based on man-made vitreous fibers (MMVF) which arebonded by a formaldehyde-free polymeric binder system.

In one aspect of the collector, the MMVF may comprise one or more fibersselected from glass wool, glass filaments, ceramic fibers, basaltfibers, slag wool, stone wool and rock wool.

In another aspect, the insulation may comprise black mineral wool.

In yet another aspect, the formaldehyde-free polymeric binder system maycomprise a water-soluble reaction product of an alkanolamine with acarboxylic anhydride which is obtainable by reacting at least onealkanolamine with at least one carboxylic anhydride and, optionally,treating the reaction product with a base.

In a still further aspect, the formaldehyde-free polymeric binder systemmay comprise:

(a) a polyacid component having acid groups, or anhydride or saltderivatives thereof; and

(b) a polyhydroxy component having hydroxyl groups.

The pH of the binder composition may be greater than about 7 and/or notgreater than about 10. Further, the ratio of the number of molarequivalents of acid groups, or anhydride or salt derivatives thereof,present on the polyacid component to the number of molar equivalents ofhydroxyl groups present on the polyhydroxy component may be from about0.6:1 to about 1.2:1.

In another aspect, the formaldehyde-free polymeric binder system maycomprise a heat-curable aqueous composition comprising

(a) at least one carboxyl-containing addition copolymer synthesized from

-   -   from about 50% to about 99.5% by weight of at least one        ethylenically unsaturated mono- and/or dicarboxylic acid,    -   from about 0.5% to about 50% by weight of at least one        ethylenically unsaturated compound selected from esters of        ethylenically unsaturated monocarboxylic acids and monoesters        and diesters of ethylenically unsaturated dicarboxylic acids        with an amine having at least one hydroxyl group,        (b) up to about 20% by weight of at least one monomer,        (c) at least one β-hydroxyalkylamine of relatively high        functionality, and        (d) optionally, at least one surfactant.

In another aspect of the solar collector of the present invention, thepolymeric binder system may be present in an amount of from about 0.1%to about 10% by weight of the bonded mineral wool insulation in a drystate.

In another aspect, the polymeric binder system may be present in aconcentration gradient over a thickness of the mineral wool insulationsuch that a concentration of the binder system is lowest in an upperregion next to the absorber of the collector and is higher in a lowerregion adjacent to the housing of the collector.

In another aspect of the collector, the mineral wool insulation may havea thermal conductivity of ≦about 0.040 W/mK and/or a bulk density offrom about 10 to about 120 kg/m³.

The present invention also provides a solar heating system whichcomprises the solar collector of the present invention as set forthabove, including the various aspects thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further described in the detailed descriptionwhich follows, in reference to the drawings by way of non-limitingexamples of exemplary embodiments of the present invention, wherein theonly FIGURE is a schematic representation of a typical flat platecollector.

DETAILED DESCRIPTION OF THE INVENTION

The particulars shown herein are by way of example and for purposes ofillustrative discussion of the embodiments of the present invention onlyand are presented in the cause of providing what is believed to be themost useful and readily understood description of the principles andconceptual aspects of the present invention. In this regard, no attemptis made to show structural details of the present invention in moredetail than is necessary for the fundamental understanding of thepresent invention, the description in combination with the drawingmaking apparent to those skilled in the art how the several forms of thepresent invention may be embodied in practice.

The present inventors have found that when using a formaldehyde-freepolymeric binder system, “fogging” of the solar collector caneffectively be prevented. For instance, usually there is no significantreduction of transmittancy of the transparent cover of a flat platecollector within the critical wavelength range of between about 0.2 μmand about 2.5 μm. The solar collectors according to the presentinvention may therefore be produced in an economical manner withoutrequiring means for avoiding or removing any hazardous emissions.Furthermore, it has been found that the mineral wool solar collectorinsulation according to the present invention exhibits superiordimensional stability as compared to a needle-punched or stitchedmineral wool mats.

The solar collector according to the present invention comprises amineral wool insulation based on man-made vitreous fibers (MMVF) whichare bonded by a formaldehyde-free polymeric binder system. The otherelements of the solar collector and its design and construction featuresare the same as with the conventional solar collectors describedherein-above.

Absorber

For instance, the preferred absorbers are made of copper or aluminum.Absorbers are usually black, as dark surfaces exhibit a particularlyhigh degree of light absorption. In order to reduce energy loss throughheat emission, the most efficient absorbers have a selective surfacecoating. This coating enables the conversion of a high proportion of thesolar radiation into heat, simultaneously reducing the emission of heat.

The absorber coating on both unglazed and glazed solar collectorabsorber plates must be stable and durable to withstand the weatherexposure of unglazed collectors and the stagnation temperatures ofglazed collectors without outgassing. For either type, the paint andprimer should be baked, and must be a top quality coating material suchas polyceram or epoxy. The most secure paint and primer bonding isobtained by using an electrostatic painting process. For collectorsintended to operate in the upper end of the medium temperature range andin the high temperature range, selective absorber coating is worthwhile,because it reduces radiation losses significantly. The most effectiveselective coating is black chrome, applied by an electroplating processover a nickel base. If applied on a material other than copper, theplating must be applied to both sides to avoid corrosion. Othergalvanically applied selective coatings include black nickel, andaluminum oxide with nickel. Another example of a suitable coating is atitanium-nitride-oxide layer, which is applied via steam in a vacuumprocess.

The tubes carrying the heat transfer medium (e.g. water or ananti-freeze solution such as water/glycol) may be soldered, brazed,snapped into grooves or inserted into spring-loaded extrusions. Widespacing of tubes reduces collector cost, while close spacing increasescost, but improves efficiency. Cost effective collectors have sufficientspacing typically of no more than about 10 cm, preferably in a parallelgrid arrangement of tubes. Another highly desirable design andconstruction feature is secure attachment of headers to water tubes.High quality collectors have the tubes brazed or welded to the headersand supported mechanically by insertion into sockets extracted directlyfrom the header metal. In addition to high level insurance againstleaks, and breakage at joints and from wind vibration, this method ofattachment provides smooth easily balanced flow and reduces thepossibility of corrosion.

Transparent Cover

The most preferred glazing material for the transparent cover in termsof service life and maintained transmissivity is tempered plate glass,borosilicate glass or Pyrex®. Of the various grades of tempered plateglass, low-iron glass has the highest transmission and lowest reflectionof sunlight. These properties result in significant increases incollector efficiency.

The glazing material may also comprise glass having a structuredsurface. The structured glass surface will prevent direct reflections(of sunlight, for example), thereby suppressing an undesired mirroreffect. Additionally, a structured glass surface will obscure directview of the interior of the collector.

Housing

The housing is used to contain the insulation, provide support for theabsorber and glazing, and to protect the collector from heat loss due towind, plus the important function of keeping moisture out of theinsulation from rain and dew. The housing may be made of a broad varietyof materials and designs, including wood cases, aluminum extrusions withsheet aluminum back, galvanized steel, welded or formed, and evencollectors without back covers. Whatever the case material andconstruction, it must be weather resistant, fireproof, durable,dimensionally stable, strong and completely and permanently sealedagainst moisture intrusion. Steel should be both galvanized and primedbefore painting and baking and paint should be tough andscratch-resistant. Aluminum should be used with caution in areas exposedto salt air or industrial pollution and smog in the air. Top-qualitycollectors use cases or frames of architectural anodized aluminumsimilar to those used for exterior windows.

Insulation

The mineral wool insulation of the solar collector according to thepresent invention is based on man-made vitreous fibers (MMVF) which arebonded by a formaldehyde-free polymeric binder system.

Suitable MMVF comprise, for instance, glass wool, glass filaments,ceramic fibers, basalt fibers, slag wool, stone wool, rock wool andother types of man-made vitreous fibers. Black (e.g. iron-containing)mineral wool is also useful for the purposes of the present invention.

The term “formaldehyde-free” as used in connection with the bindersystem, is meant to indicate that the binder composition issubstantially free of formaldehyde, and does not liberate substantialamounts of formaldehyde as a result of drying and/or curing. Typically,less than about 1 ppm formaldehyde, based on the weight of thecomposition, is present in a formaldehyde-free composition.

FIRST EMBODIMENT OF MMVF BINDER

In a first embodiment of the present invention, the formaldehyde-freepolymeric binder system comprises the water-soluble reaction product ofan alkanolamine with a carboxylic anhydride obtainable by reacting atleast one alkanolamine with at least one carboxylic anhydride and,optionally, treating the reaction product with a base.

Preferred examples of alkanolamines for use in the preparation of thisbinder system include alkanolamines having at least two hydroxy groupssuch as, for instance, alkanolamines represented by the formula

wherein R¹ is hydrogen, a C₁₋₁₀ alkyl group or a C₁₋₁₀ hydroxyalkylgroup; and R² and R³ independently are C₁₋₁₀ hydroxyalkyl groups.

Preferably, R² and R³ independently are C₂₋₅ hydroxyalkyl groups, and R¹is hydrogen, a C₁₋₅ alkyl group or a C₂₋₅ hydroxyalkyl group.Particularly preferred hydroxyalkyl groups include β-hydroxyalkylgroups.

Specific and non-limiting examples of suitable alkanolamines includediethanolamine, triethanolamine, diisopropanolamine,triisopropanolamine, methyldiethanolamine, ethyldiethanolamine,n-butyldiethanolamine, methyldiisopropanolamine, ethyl-isopropanolamine,ethyldiisopropanolamine, 3-amino-1,2-propanediol,2-amino-1,3-propanediol and tris(hydroxymethyl)aminomethane.Diethanolamine is the currently preferred alkanolamine.

The carboxylic anhydride reactant may be selected from saturated orunsaturated aliphatic and cycloaliphatic anhydrides, aromatic anhydridesand mixtures thereof, saturated or unsaturated cycloaliphaticanhydrides, aromatic anhydrides and mixtures thereof being preferred. Ina particularly preferred embodiment of the invention, two differentanhydrides selected from cycloaliphatic and/or aromatic anhydrides areemployed. These different anhydrides are preferably reacted in sequence.

Specific and non-limiting examples of suitable aliphatic carboxylicanhydrides include succinic anhydride, maleic anhydride and glutaricanhydride. Specific and non-limiting examples of suitable cycloaliphaticanhydrides include tetrahydrophthalic anhydride, hexahydrophthalicanhydride, methyltetrahydrophthalic anhydride and nadic anhydride, i.e.endo-cis-bicyclo[2.2.1]-5-heptene-2,3-dicarboxylic anhydride. Specificand non-limiting examples of suitable aromatic anhydrides includephthalic anhydride, methylphthalic anhydride, trimellitic anhydride andpyromellitic dianhydride.

If two different anhydrides are employed, a combination ofcycloaliphatic anhydride and aromatic anhydride is particularlypreferred, e.g. a combination of tetrahydrophthalic anhydride (THPA) andtrimellitic anhydride (TMA). The molar ratio of cycloaliphatic anhydrideto aromatic anhydride is preferably within the range of from about 0.1:1to about 10:1, more preferably within the range of from about 0.5:1 toabout 3:1. Curing tests with the system THPA/TMA have surprisingly shownthat a lower molar ratio of THPA to TMA results in a higher curingspeed.

In the preparation of the binder composition, the proportion of thealkanolamine and carboxylic anhydride reactants is preferably selectedsuch that the ratio of equivalents of amine plus hydroxy groups (NH+OH)to equivalents of carboxy groups (COOH) is at least about 0.4, morepreferably at least about 0.6. By employing these minimum ratios, toohigh an excess of free unreacted acid is avoided which under specificconditions might lead to a displacement of binder in the curing oven,i.e. to a non-uniform distribution in the amount of binder between thebottom and top of the mineral wool mat or web. Furthermore, high amountsof unreacted acid may increase corrosiveness.

On the other hand, the properties of the final binder composition, suchas curing behaviour, durability and humidity resistance are determinedby the total ratio of reactive groups present. Therefore, for optimumperformance, the ratio of equivalents of amine plus hydroxy groups(NH+OH) to equivalents of carboxy groups (COOH) in the final bindercomposition is preferably adjusted to about 2.0 or less, more preferablyto about 1.7 or less. In general, the final binder composition has anequivalent ratio of (NH+OH)/(COOH) within the range of from about 1.25to about 1.55.

The reaction between the alkanolamine and carboxylic anhydride reactantsis carried out in the usual manner, for instance, as described in WO99/36368, WO 01/05725, WO 01/96460, WO 02/06178, WO 2004/007615 and WO2006/061249, the entire disclosures whereof are incorporated byreference herein.

The reaction temperature is generally within the range of from about 50°C. to about 200° C. In a preferred embodiment and, in particular, whentwo different anhydrides are employed, the alkanolamine is first heatedto a temperature of at least about 40° C., preferably at least about 60°C., whereafter the first anhydride is added and the reaction temperatureis raised to at least about 70° C., preferably at least about 95° C. andmore preferably at least about 125° C., at which temperature the secondanhydride is added to the reaction mixture when substantially all thefirst anhydride has dissolved and/or reacted. Increasing the reactiontemperature from about 70-95° C. to about 100-200° C. allows a higherconversion of monomers to oligomers. In this case, a preferredtemperature range is about 105-170° C., more preferably about 110-150°C.

If water is added after the first anhydride has reacted, either togetherwith the second anhydride or before addition of the second anhydride orat the end of the reaction, in an amount to make the binder easilypumpable, a binder having an increased molecular weight (compared towater addition from the start) is obtained which still has a desiredpumpability, viscosity, and water dilutability and contains lessunreacted monomers.

In order to improve the water solubility and dilutability of the binder,a base may be added up to a pH of about 8, preferably a pH of from about5 to about 8, and more preferably a pH of about 6. Furthermore, theaddition of a base will cause at least partial neutralization ofunreacted acids and a concomitant reduction of corrosiveness. Normally,the base will be added in an amount sufficient to achieve the desiredwater solubility or dilutability. The base is preferably selected fromvolatile bases which will evaporate at or below curing temperature andhence will not influence curing. Specific and non-limiting examples ofsuitable bases include ammonia (NH₃) and organic amines such asdiethanolamine (DEA), triethanolamine (TEA) and dimethylethanolamine(DMEA). The base is preferably added to the reaction mixture after thereaction between the alkanol amine and the carboxylic anhydride has beenactively stopped by adding water.

If appropriate, an additional acid monomer may be employed in thereaction and is preferably added to the reaction mixture before additionof the anhydride reactant. Specific and non-limiting examples ofsuitable acid monomers include di-, tri- and polycarboxylic acids suchas adipic acid, citric acid, sebacic acid, azelaic acid, succinic acid,tartaric acid and trimellitic acid.

Furthermore, one or more polycarboxy crosslinking agents may be addedafter termination of the reaction and, optionally, together with thebase. Suitable polycarboxy crosslinking agents include, e.g.,homopolymers and copolymers of acidic monomers such as acrylic acid,alkylacrylic acid (e.g. methacrylic acid) and maleic acid, andcopolymers of such acidic monomers and acrylates. The weight percentageof these polycarboxy crosslinking agents is at least about 0.5%,preferably at least about 10 wt. %, and up to about 50%, preferably upto about 30 wt. %, more preferably up to about 15 wt. %, based on thebinder composition.

SECOND EMBODIMENT OF MMVF BINDER

In a second aspect of the present invention, the formaldehyde-freepolymeric binder system comprises an aqueous binder compositioncomprising:

(a) a polyacid component having acid groups, or anhydride or saltderivatives thereof; and

(b) a polyhydroxy component having hydroxyl groups;

wherein the pH of the binder composition is greater than about 7 and ispreferably within the range of from about 7 to about 10.

In an exemplary embodiment, the composition includes a polyacidcomponent and a polyhydroxy component where the ratio of the number ofmolar equivalents of acid groups, or anhydride or salt derivativesthereof, present on the polyacid component to the number of molarequivalents of hydroxyl groups present on the polyhydroxy component isin the range of from about 0.6:1 to about 1.2:1.

In another exemplary embodiment, the composition includes a polyacidcomponent that is a dicarboxylic acid, including, but not limited to,unsaturated aliphatic dicarboxylic acids, saturated aliphaticdicarboxylic acids, aromatic dicarboxylic acids, unsaturated cyclicdicarboxylic acids, saturated cyclic dicarboxylic acids,hydroxy-substituted derivatives thereof, and the like. In anotherexemplary embodiment, the composition includes a polyacid component thatis a tricarboxylic acid, including, but not limited to, unsaturatedaliphatic tricarboxylic acids, saturated aliphatic tricarboxylic acids,aromatic tricarboxylic acids, unsaturated cyclic tricarboxylic acids,saturated cyclic tricarboxylic acids, hydroxy-substituted derivativesthereof, and the like. In another exemplary embodiment, the compositionincludes a polyacid component that comprises one or more oftetracarboxylic, pentacarboxylic, and like polycarboxylic acids, andsalts and anhydride derivatives thereof, and combinations thereof. It isto be appreciated that any of these polyacids may be optionallysubstituted, such as with hydroxy, halo, alkyl, alkoxy, and the like.

Exemplary polyacid components include dicarboxylic acids, such as, forexample, maleic acid. Other examples of suitable polyacid componentsinclude, but are not limited to, aconitic acid, adipic acid, azelaicacid, butane tetracarboxylic acid dihydride, butane tricarboxylic acid,chlorendic acid, citraconic acid, citric acid, dicyclopentadiene-maleicacid adducts, diethylenetriaminepentaacetic acid, adducts of dipenteneand maleic acid, endomethylenehexachlorophthalic acid, ethylenediaminetetraacetic acid (EDTA), fully maleated rosin, maleated tall oil fattyacids, fumaric acid, glutaric acid, isophthalic acid, itaconic acid,maleated rosin-oxidize unsaturation with potassium peroxide to alcoholthen carboxylic acid, malic acid, mesaconic acid, biphenol A orbisphenol F reacted via the KOLBE-Schmidt reaction with carbon dioxideto introduce 3-4 carboxyl groups, oxalic acid, phthalic acid,polylacetic acid, sebacic acid, succinic acid, tartaric acid,terephthalic acid, tetrabromophthalic acid, tetrachlorophthalic acid,tetrahydrophthalic acid, trimellitic acid, and trimesic acid, andanhydrides and salts thereof, and combinations thereof.

In an exemplary embodiment, the acid groups of the polyacid component ofthe formaldehyde-free, thermally curable, alkaline, aqueous bindercomposition are neutralized with a base, and thereby converted to acidsalt groups, prior to their reaction with the hydroxyl groups of thepolyhydroxy component to form the polyester resin. It is understood thatcomplete neutralization, i.e., about 100% calculated on an equivalentsbasis, may eliminate any need to titrate or partially neutralize acidgroups in the polyacid component prior to polyester formation, but it isanticipated that less-than-complete neutralization would not inhibitformation of the polyester.

The term “base” as used herein refers to a base which may besubstantially volatile or non-volatile under conditions which aresufficient to promote a formation of the polyester. Illustratively, thebase may be a volatile base, such as, for example, aqueous ammonia;alternatively, the base may be a non-volatile base, such as, forexample, sodium carbonate, and other non-volatile bases, such as sodiumhydroxide, potassium hydroxide, and the like. Neutralization may becarried out either before or after the polyacid component is mixed withthe polyhydroxy component.

In one aspect, the composition may be an alkaline composition, where thepolyacid component is neutralized by the addition of a base or wherecertain salts of the polyacid component are used. In another exemplaryembodiment, the composition may include a polyacid component, such assuccinic acid, citric acid, or fumaric acid and the like that has beenneutralized by the addition of a base, or is a salt. In anotherexemplary embodiment, the polyacid component may be maleic acidneutralized with, for example, aqueous ammonia. In another exemplaryembodiment, the polyacid component may be the ammonium salt of maleate.

The formaldehyde-free, thermally curable, alkaline, aqueous bindercomposition also includes a polyhydroxy component having hydroxylgroups. In one aspect, the polyhydroxy component is sufficientlynonvolatile to maximize its ability to remain available for reactionwith the polyacid component. The polyhydroxy component may be apolyvinyl alcohol, a partially hydrolyzed polyvinyl acetate, such as,for example, an ELVANOL® (available from DuPont Packaging and IndustrialPolymers; Wilmington, Del., USA), or a mixture thereof.

In an exemplary embodiment, the formaldehyde-free, thermally curable,alkaline, aqueous binder composition may also include a catalyst capableof increasing the rate of polyester formation during curing of thebinder compositions described herein. Illustratively, the catalyst maybe an ammonium salt, such as, for example, ammonium para-toluenesulfonate or ammonium naphthalene disulfonate. Other suitable catalystsare contemplated to include, but are not limited to, ammonium sulfate,ammonium chloride, sulfuric acid, lacetic acid, lead acetate, sodiumacetate, calcium acetate, zinc acetate, organotin compounds, titaniumesters, antimony trioxide, germanium salts, sodium hypophosphite, sodiumphosphite, methanesulfonic acid and para-toluenesulfonic acid, andmixtures thereof.

In an exemplary embodiment, the formaldehyde-free, thermally curable,alkaline, aqueous binder composition may also include asilicon-containing coupling agent, e.g., an organosilicon oil, asilylether or alkylsilyl ether. In one aspect, the silicon-containingcompound may be an amino-substituted silane, such as, for example,gamma-aminopropyltriethoxy silane.

As described in WO 2005/087837, the entire disclosure whereof isincorporated by reference herein, the formaldehyde-free, thermallycurable, alkaline, aqueous binder composition according to the secondembodiment may be prepared by admixing an about 10-50 weight percentaqueous solution of a polyacid component, already neutralized orneutralized in the presence of the polyhydroxy component, an about 10-30weight percent aqueous solution of a polyhydroxy component, and, ifdesired, an aqueous solution of a catalyst capable of increasing therate of polyester formation during curing, and also, if desired, asilicon-containing coupling agent. By varying the polyacid component,the polyhydroxy component, and optional catalyst and silicon-containingcoupling agent compositions, the initial concentrations thereof, and themixing ratio of solutions, a wide range of binder solution compositionscan be prepared, wherein the pH of the binder composition is alkaline,and preferably in the range of from about 7 to about 10.

THIRD EMBODIMENT OF MMVF BINDER

In a third aspect of the present invention, the formaldehyde-freepolymeric binder system comprises a binder composition comprising apolycarboxy polymer (especially a polyacrylic acid polymer), apolyhydroxy crosslinking agent, and a surfactant selected from cationicsurfactants, amphoteric surfactants, nonionic surfactants, and mixturesthereof.

The binder composition is prepared by polymerization of monomers(preferably acrylic acid) emulsified in water using conventionalemulsion polymerization procedures. Suitable surfactants are used foremulsification of the monomers, including cationic, amphoteric ornonionic surfactants, and mixtures thereof, with nonionic surfactantsbeing preferred.

The binder composition comprises an organic polymer or oligomercontaining a plurality of pendant carboxy groups which may be ahomopolymer or copolymer prepared from unsaturated carboxylic acidsincluding acrylic acid, methacrylic acid, crotonic acid, isocrotonicacid, maleic acid, cinnamic acid, 2-methylmaleic acid, itaconic acid,2-methylitaconic acid, and the like. Alternatively, the polycarboxypolymer may be prepared from unsaturated anhydrides including maleicanhydride, itaconic anhydride, acrylic anhydride, methacrylic anhydride,and the like, as well as mixtures thereof.

The low molecular weight polycarboxy polymer produced in the first stepof the process is reacted with a polyhydroxy crosslinking agent, such astriethanolamine, glycerol, trimethylolpropane, 1,2,4-butanetriol,ethyleneglycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol,pentaerythritol, sorbitol, and the like. No catalyst is necessary inthis crosslinking step.

The polycarboxy polymer, polyhydroxy crosslinking agent and surfactantmay be mixed in a conventional mixing device. The polycarboxy polymermay be present at a concentration of from about 5% to about 50% byweight, preferably of from about 10% to about 30% by weight, based onthe total weight of the mixture. Water may be added to the solidsmixture in any amount which would produce an aqueous binder having aviscosity and flow rate suitable for its application to a formingfibrous glass mat by any convenient method, such as by spraying.Conveniently, water may comprise up to about 98% by weight of thebinder.

Non-limiting examples of useful cationic surfactants include alkylaminesalts such as laurylamine acetate, quaternary ammonium salts such aslauryl trimethyl ammonium chloride and alkyl benzyl dimethylammoniumchlorides, and polyoxyethylene-alkylamines. Non-limiting examples of theamphoteric surfactants include alkyl betaines such as lauryl betaine.

Non-limiting examples of suitable nonionic surfactants includepolyethers, e.g., ethylene oxide and propylene oxide condensates whichinclude straight and branched chain alkyl and alkaryl polyethyleneglycol and polypropylene glycol ethers and thioethers;alkylphenoxypoly(ethyleneoxy)ethanols having alkyl groups containingfrom about 7 to about 18 carbon atoms and having from about 4 to about240 ethyleneoxy units, such as heptylphenoxy poly(ethyleneoxy)ethanols,nonylphenoxy poly(ethyleneoxy)ethanols; the polyoxyalkylene derivativesof hexitol including sorbitans, sorbides, mannitans, and mannides;partial long-chain fatty acids esters, such as the polyoxyalkylenederivatives of sorbitan monolaurate, sorbitan monopalmitate, sorbitanmonostearate, sorbitan tristearate, sorbitan monooleate, and sorbitantrioleate; the condensates of ethylene oxide with a hydrophobic base,said base being formed by condensing propylene oxide with propyleneglycol; sulfur containing condensates, e.g., those prepared bycondensing ethylene oxide with higher alkyl mercaptans, such as nonyl,dodecyl, or tetradecyl mercaptan, or with alkylthiophenols wherein thealkyl group contains from about 6 to about 15 carbon atoms; ethyleneoxide derivatives of long-chain carboxylic acids, such as lauric,myristic, palmitic, or oleic acids or mixtures of acids, such as talloil fatty acids; ethylene oxide derivatives of long-chain alcohols suchas octyl, decyl, lauryl, or cetyl alcohols; and ethylene oxide/propyleneoxide copolymers.

The amounts of surfactants employed in the emulsion polymerizationprocess will range from about 0.01 to about 10 weight percent,preferably about 0.2 to about 5 weight percent based on the total weightof monomers and water.

As described in US Patent No. 2004/0152824, the entire disclosurewhereof is incorporated by reference herein, the polyacrylic acid andthe polyhydroxy crosslinking agent may be mixed with water in aconventional mixing device. Water may be added to the mixture of acrylicacid monomer and polyhydroxy crosslinking agent in any amount whichproduces an aqueous binder mixture having a viscosity and flow ratesuitable for application to a forming fibrous glass mat by anyconvenient method, e.g., spraying.

FOURTH EMBODIMENT OF MMVF BINDER

In a fourth aspect of the present invention, the formaldeyhde-freepolymeric binder system comprises a heat-curable aqueous compositioncomprising

at least one carboxyl-containing addition copolymer synthesized from

from about 50% to about 99.5% by weight of at least one ethylenicallyunsaturated mono- and/or dicarboxylic acid,

from about 0.5% to about 50% by weight of at least one ethylenicallyunsaturated compound selected from esters of ethylenically unsaturatedmonocarboxylic acids and monoesters and diesters of ethylenicallyunsaturated dicarboxylic acids with an amine having at least onehydroxyl group,

up to about 20% by weight of at least one further monomer,

at least one β-hydroxyalkylamine of relatively high functionality, and

if desired, at least one surfactant.

The carboxyl-containing copolymers used in these binder compositionstherefore incorporate from about 50% to about 99.5% by weight,preferably from about 70% to about 99% by weight, of structural unitsderived from ethylenically unsaturated monocarboxylic acids,ethylenically unsaturated dicarboxylic acids and/or their monoesterswith C₁ to C₂₂ alkanols. In the copolymer, these acids may be wholly orpartly in the form of a salt. The acidic form is preferred.

In the preparation of the carboxyl-containing copolymer, it is possibleto use not only the above-mentioned monomers but also the anhydrides ofthe ethylenically unsaturated monocarboxylic acids and the anhydrides ofthe ethylenically unsaturated dicarboxylic acids.

Particularly preferred monomers for preparing the carboxyl-containingcopolymers include maleic acid, maleic anhydride, acrylic acid,methacrylic acid, acrylic anhydride, methacrylic anhydride, itaconicacid, tetrahydrophthalic acid and the anhydrides thereof, and also thealkali metal salts and ammonium salts or mixtures thereof.

With particular preference, the copolymer incorporates structuralelements derived from acrylic acid or of a mixture of acrylic acid andmaleic acid in a ratio of from about 95:5 to about 40:60, in particularin a ratio of from about 90:10 to about 50:50.

The copolymer used in the compositions further contains from about 0.5%to about 50% by weight, preferably from about 1% to about 30% by weight,of at least one ethylenically unsaturated compound selected from estersof ethylenically unsaturated monocarboxylic acids and monoesters anddiesters of ethylenically unsaturated dicarboxylic acids with at leastone hydroxyl-containing amine, in copolymerized form.

Examples of monocarboxylic acids which are suitable as components of theesters include the above-mentioned C₃ to C₁₀ monocarboxylic acids,especially acrylic acid, methacrylic acid, crotonic acid and mixturesthereof.

Examples of dicarboxylic acids which are suitable as components of themonoesters and diesters include the above-mentioned C₄ to C₈dicarboxylic acids, especially fumaric acid, maleic acid, 2-methylmaleicacid, itaconic acid, and mixtures thereof.

The amine having at least one hydroxyl group is preferably selected fromsecondary and tertiary amines containing at least one C₆ to C₂₂ alkyl,C₆ to C₂₂ alkenyl, aryl-C₆ to C₂₂ alkyl or aryl-C₆ to C₂₂ alkenylradical, it being possible for the alkenyl group to have 1, 2 or 3nonadjacent double bonds.

The amine is preferably hydroxyalkylated and/or alkoxylated. Alkoxylatedamines preferably have one or two alkylene oxide residues with terminalhydroxyl groups. Preferably, the alkylene oxide residues each have fromabout 1 to about 100, preferably from about 1 to about 50, identical ordifferent alkylene oxide units, distributed randomly or in the form ofblocks. Preferred alkylene oxides are ethylene oxide, propylene oxideand/or butylene oxide. Ethylene oxide is particularly preferred.

The polymer preferably comprises an unsaturated compound based on anamine component incorporating at least one amine of the formulaR^(c)NR^(a)R^(b)

where

R^(c) is C₆ to C₂₂ alkyl, C₆ to C₂₂ alkenyl, aryl-C₆-C₂₂ alkyl oraryl-C₆-C₂₂ alkenyl, it being possible for the alkenyl radical to have1, 2 or 3 nonadjacent double bonds,

R^(a) is hydroxy-C₁-C₆ alkyl or a radical of the formula II—(CH₂CH₂O)_(x)(CH₂CH(CH₃)O)_(y)—H  (II)

where

in the formula II the sequence of the alkylene oxide units is arbitraryand x and y independently of one another are integers from 0 to about100, preferably from 0 to about 50, the sum of x and y being >1,

R^(b) is hydrogen, C₁ to C₂₂ alkyl, hydroxy-C₁-C₆ alkyl, C₆ to C₂₂alkenyl, aryl-C₆-C₂₂ alkyl, aryl-C₆-C₂₂ alkenyl or C₅ to C₈ cycloalkyl,it being possible for the alkenyl radical to have 1, 2 or 3 nonadjacentdouble bonds,

or R^(b) is a radical of the formula III—(CH₂CH₂O)_(v)(CH₂CH(CH₃)O)_(w)—H  (III)

where

in the formula III the sequence of the alkylene oxide units is arbitraryand v and w independently of one another are integers from 0 to about100, preferably from 0 to about 50.

Preferably R^(c) is C₈ to C₂₀ alkyl or C₈ to C₂₀ alkenyl, it beingpossible for the alkenyl radical to have 1, 2 or 3 nonadjacent doublebonds. R^(c) is preferably the hydrocarbon radical of a saturated ormono- or polyunsaturated fatty acid. Preferred radicals R^(c) include,for example, n-octyl, ethylhexyl, undecyl, lauryl, tridecyl, myristyl,pentadecyl, palmityl, margarinyl, stearyl, palmitoleinyl, oleyl andlinolyl.

With particular preference, the amine component comprises an alkoxylatedfatty amine or an alkoxylated fatty amine mixture. The ethoxylates areparticularly preferred. Use is made in particular of alkoxylates ofamines based on naturally occurring fatty acids, such as tallow fattyamines, for example, which contain predominantly saturated andunsaturated C₁₄, C₁₆ and C₁₈ alkylamines, or cocoamines, containingsaturated, mono- and diunsaturated C₆-C₂₂, preferably C₁₂-C₁₄alkylamines.

Copolymerization of the above-mentioned esters, monoesters and diestersgenerally brings about a reduction in the surface tension of thecompositions.

The esterification reaction for preparing the above-described esters,monoesters and diesters takes place in accordance with customarytechniques. To prepare esters of unsaturated monocarboxylic acids, thefree acids or suitable derivatives, such as anhydrides, halides, e.g.,chlorides, and C₁ to C₄ alkyl esters may be used. The preparation ofmonoesters of unsaturated dicarboxylic acids takes place preferablystarting from the corresponding dicarboxylic anhydrides. The reaction ispreferably effected in the presence of a catalyst, such as a dialkyltitanate or an acid, such as sulfuric acid, toluenesulfonic acid, ormethanesulfonic acid, for example. The reaction takes place generally atreaction temperatures from about 60 to about 200° C. In accordance withone suitable embodiment, the reaction takes place in the presence of aninert gas, such as nitrogen. Water formed during the reaction may beremoved from the reaction mixture by means of appropriate measures, suchas distillation. The reaction may take place if desired in the presenceof customary polymerization inhibitors. Essentially, the esterificationreaction may be conducted to completion or just to a partial conversion.If desired, one of the ester components, preferably thehydroxyl-containing amine, may be used in excess. The extent ofesterification may be determined by means of infrared spectroscopy.

In one preferred embodiment, the unsaturated esters, monoesters ordiesters are prepared and further reacted to the copolymers withoutisolation of the esters, the reactions preferably taking place insuccession in the same reaction vesssel.

To prepare the copolymers it is preferred to use a reaction product of adicarboxylic anhydride, preferably maleic anhydride, and one of theabove-described hydroxyl-containing amines.

The polymers may advantageously also be prepared by means ofpolymer-analogous reaction. For this purpose a polymer incorporatingfrom about 80% to about 100% by weight of at least one ethylenicallyunsaturated mono- and/or dicarboxylic acid may be reacted with at leastone hydroxyl-containing amine.

Examples of suitable ethylenically unsaturated mono- and dicarboxylicacids include those mentioned above. Suitable amines having at least onehydroxyl group are likewise as mentioned above. In the polymer suitablefor polymer-analogous reaction, the acids may, if desired, be presentwholly or partly in the form of a derivative, preferably a C₁ to C₆alkyl ester.

In one suitable embodiment, the copolymers incorporate as furthermonomer at least one compound selected from olefins, preferablyethylene, propene, n-butene, isobutene and/or diisobutene, vinylaromaticcompounds, preferably styrene, esters of α,β-ethylenically unsaturatedmono- and/or dicarboxylic acids with C₁ to C₂₂ alkanols, preferably(meth)acrylic esters, and mixtures thereof.

Preferred further monomers include

linear and branched-chain 1-olefins or cyclic olefins such as ethylene,propene, butene, isobutene, diisobutene, pentene, cyclopentene, hexene,cyclohexene, octene, and 2,4,4-trimethyl-1-pentene, alone or mixed with2,4,4-trimethyl-2-pentene, C₈ to C₁₀ olefin, 1-dodecene, C₁₂ to C₁₄olefin, octadecene, 1-eicosene (C₂₀), C₂₀ to C₂₄ olefin; oligoolefinsprepared with metallocene catalysis and having a terminal double bond,such as oligopropene, oligohexene and oligooctadecene; olefins preparedby cationic polymerization and having a high α-olefin content, such aspolyisobutene, for example;

esters of preferably C₃ to C₆ α,β-monoethylenically unsaturated mono- ordicarboxylic acids, such as acrylic acid, methacrylic acid, maleic acid,fumaric acid, and itaconic acid, with C₁-C₁₂, preferably C₁-C₈ alkanols.Such esters are in particular methyl, ethyl, n-butyl, isobutyl,tert-butyl, n-pentyl, isopentyl and 2-ethylhexyl acrylate and/ormethacrylate;

vinylaromatic compounds, preferably styrene, α-methylstyrene,o-chloro-styrene, vinyltoluenes and mixtures thereof.

Particularly preferred further monomers include ethylene, propene,isobutene, diisobutene, styrene, methyl (meth)acrylate, ethyl(meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, andmixtures thereof. The copolymers are prepared preferably by free-radicaladdition polymerization in bulk or in solution.

Preparation by solution polymerization takes place generally in water assolvent. It is, however, also possible for water-miscible organicsolvents, such as alcohols and ketones, e.g., methanol, ethanol,n-propanol, isopropanol, n-butanol, acetone or methyl ethyl ketone, tobe present in a proportion of up to approximately 30% by volume.

The polymerization is preferably conducted in the presence of compoundswhich form free radicals (initiators). The amount required of thesecompounds is preferably from about 0.05% to about 10%, with particularpreference from about 0.2% to 5% by weight, based on the monomers usedin the polymerization.

Examples of suitable polymerization initiators include peroxides,hydroperoxides, peroxodisulfates, percarbonates, peroxo esters, hydrogenperoxide, and azo compounds. Examples of initiators, which can besoluble in water or else insoluble in water, include hydrogen peroxide,dibenzoyl peroxide, dicyclohexyl peroxodicarbonate, dilauroyl peroxide,methyl ethyl ketone peroxide, di-tert-butyl peroxide, acetylacetoneperoxide, tert-butyl hydroperoxide, cumene hydroperoxide, tert-butylpemeodecanoate, tert-amyl perpivalate, tert-butyl perpivalate,tert-butyl pemeohexanoate, tert-butyl per-2-ethylhexanoate, tert-butylperbenzoate, lithium, sodium, potassium and ammonium peroxodisulfates,azodiisobutyronitrile, 2,2′-azobis(2-amidinopropane) dihydrochloride,2-(carbamoylazo)isobutyronitrile, and 4,4′-azobis(4-cyanovaleric acid).The known redox initiator systems, such as, e.g., H₂O₂/ascorbic acid ortert-butyl hydroperoxide/sodium hydroxymethanesulfinate, can be used aspolymerization initiators as well.

The initiators can be employed alone or in a mixture with one another,examples being mixtures of hydrogen peroxide and sodium peroxodisulfate.For polymerization in an aqueous medium it is preferred to usewater-soluble initiators.

In addition to the above-described carboxyl-containing polymers, theheat-curable aqueous compositions according to the fourth embodimentfurther comprise at least one β-hydroxylamine of relatively highfunctionality. The weight ratio between copolymer andβ-hydroxyalkylamine is preferably from about 1:1 to about 1:0.01, morepreferably from about 1:1 to about 1:0.1.

Appropriate higher-functional β-hydroxyalkylamines include preferablycompounds of the formula

where R¹ is a hydrogen atom, a C₁ to C₁₀ alkyl group, a C₁ to C₁₀hydroxyalkyl group, or a radical of the formula IV—(CH₂CH₂O)_(x)(CH₂CH(CH₃)O)_(y)—H  (IV)

where

in the formula IV the sequence of the alkylene oxide units is arbitraryand x and y independently of one another are integers from 0 to about100, the sum of x and y being >1, and R² and R³ independently of oneanother are a C₁ to C₁₀ hydroxyalkyl group.

With particular preference, R² and R³ independently of one another are aC₂ to C₅ hydroxyalkyl group and R¹ is a hydrogen atom, a C₁ to C₅ alkylgroup or a C₂ to C₅ hydroxyalkyl group.

Particular preference is given to diethanolamine, triethanolamine,diisopropanolamine, trisopropanolamine, methyldiethanolamine,butyldiethanolamine and methyldiisopropanolamine, especiallytriethanolamine.

Further preferred β-hydroxyalkylamines are the amines disclosed ascomponent A in DE-A-19621573, the entire disclosure whereof isincorporated by reference herein. They include preferably linear orbranched aliphatic compounds containing per molecule at least twofunctional amino groups of type (a) or (b)

where R is hydroxyalkyl and R′ is alkyl, preferably a compound offormula I

where

A is C₂-C₁₈ alkylene substituted or unsubstituted by one or more groupsselected independently of one another from alkyl, hydroxyalkyl,cycloalkyl, OH and NR⁶R⁷, R⁶ and R⁷ independently of one another beinghydrogen, hydroxyalkyl or alkyl, and which is uninterrupted orinterrupted by one or more oxygen atoms and/or NR⁵ groups, R⁵ beinghydrogen, hydroxyalkyl, (CH₂)_(n)NR⁶R⁷ where n is from 2 to 5 and R⁶ andR⁷ are as defined above, or alkyl, which may in turn be interrupted byone or more NR⁵ groups, R⁵ possessing the above-mentioned definitions,and/or substituted by one or more NR⁶R⁷ groups, R⁶ and R⁷ possessing theabove-mentioned definitions;

or A is a radical of the formula:

where

o, q and s independently of one another are 0 or an integer of from 1 to6,

p and r independently of one another are 1 or 2, and

t is 0, 1 or 2,

it also being possible for the cycloaliphatic radicals to be substitutedby 1, 2 or 3 alkyl radicals, and

R¹, R² and R³ and R⁴ independently of one another are hydrogen,hydroxyalkyl, alkyl or cycloalkyl.

Preferred β-hydroxyalkylamines of relatively high functionality include,in particular, at least doubly ethoxylated amines having a molar weightof less than about 1000 g/mol, such as diethanolamine, triethanolamineand ethoxylated diethylenetriamine, for example, preferably anethoxylated diethylenetriamine, in which on average allnitrogen-attached hydrogen atoms are monoethoxylated.

In one suitable embodiment, the heat-curable aqueous composition of theinvention comprises at least one surfactant which may, but need notnecessarily be, identical with the above-described hydroxy-containingamine.

If the compositions according to the fourth embodiment comprise as atleast one additional surfactant at least one amine which corresponds tothe hydroxyl-containing amines used above to prepare the esters andmonoesters, then this amine may if desired be added separately to thecompositions or may be used in an appropriate excess during thepreparation of said esters.

As additional surfactants, the compositions preferably comprise from 0%to about 50% by weight, preferably from about 0.1% to about 40% byweight, based on the copolymer, of at least one surface-active,alkoxylated, preferably ethoxylated or propoxylated, alkylamine.Preferred alkylamines are the alkylamines of the formulaR^(c)NR^(a)R^(b), as defined above, which are also present in thecopolymer, particular preference being given to alkylamines of theformula

where R is an alkyl, alkenyl or alkylvinyl radical having at least 6carbon atoms and m and n independently of one another are ≧1. Preferredradicals R have from about 8 to about 22 carbon atoms.

Further suitable long-chain amines are also for example the ethoxylatedamines sold by AKZO as ETHOMEEN®, such as ETHOMEEN® C/15, apoly-oxyethylene-(5)-cocoamine, or ETHOMEEN® S/12, anoleylbis(2-hydroxyethyl)amine, or ETHOMEEN® T/25, apolyoxyethylene-(15)-tallowamine.

Preferred additional surfactants include ethoxylated long-chain mono-and diamines. To prepare the novel compositions use may also be made,however, of other long-chain primary, secondary or tertiary aliphaticamines. Examples are the AKZO products ARMEEN® DMOD(oleyldimethylamine), ARMEEN® M2C (dicocomethylamine), ARMEEN® NCMD(N-cocomorpholine), ARMEEN® 2C (Dicocoamine) or ARMEEN® 12D(n-dodecylamine).

If desired, the compositions according to the fourth embodiment mayfurther comprise at least one additional crosslinker. Preference isgiven to amine or amide crosslinkers which contain at least two hydroxylgroups. Preferred crosslinkers are the alkanolamines described inDE-A-19729161, the entire disclosure whereof is incorporated byreference herein, especially the β-hydroxy-alkylamides described in U.S.Pat. No. 5,143,582, the entire disclosure whereof is incorporated byreference herein, of the formula

Particularly preferred β-hydroxyalkylamides are those in which R¹ ishydrogen, a lower alkyl, or HO(R³)₂C(R²)₂C—, n and n′ are each 1, -A- is—(CH₂)_(m)—, m is from 0 to 8, preferably from 2 to 8, R² both arehydrogen, and in each case one of the R³ groups is hydrogen and theother is hydrogen or a C₁-C₅ alkyl.

As described in DE-A-19949591, the entire disclosure whereof isincorporated by reference herein, the compositions are preparedpreferably by solution polymerization in order to obtain acarboxyl-containing copolymer, followed by addition of the othercomponents of the composition. The solution polymerization preferablytakes place in water. Alternatively, it is possible to usewater-miscible organic solvents, such as alcohols and ketones, e.g.,methanol, ethanol, acetone, and their mixtures with water.

A typical process for preparing the compositions comprises

i) reacting at least one ethylenically unsaturated monocarboxylic acidor derivative thereof and/or at least one ethylenically unsaturateddicarboxylic acid or a derivative thereof with at least onehydroxyl-containing amine in an esterification reaction,

ii) reacting the reaction product(s) from step i) with at least oneethylenically unsaturated mono- and/or dicarboxylic acid and/oranhydride thereof and, if desired, at least one further monomer, to givea carboxyl-containing copolymer, and

iii) mixing the copolymer from step ii) with at least oneβ-hydroxyalkylamine of relatively high functionality, if desired, atleast one surfactant, and, if desired, further additives.

Among the four types of MMVF binders described above, the binderaccording to the first embodiment is particularly preferred owing to itsexcellent properties.

Other Components of Binder Composition

The binder compositions according to all four embodiments of presentinvention may additionally comprise one or more conventional binderadditives. These include, for instance, curing accelerators such as,e.g., β-hydroxyalkylamides; the free acid and salt forms of phosphoricacid, hypophosphorous acid, phosphonic acid, phosphinic acid, citricacid and adipic acid. Other strong acids such as boric acid, sulphuricacid, nitric acid and p-toluenesulphonic acid may also be used, eitheralone or in combination with the just mentioned acids, in particularwith phosphoric, hypophosphorous acid, phosphonic or phosphinic acid.Other suitable binder additives include silane coupling agents such asγ-aminopropyltriethoxysilane; thermal stabilizers; UV stabilizers;emulsifiers; surface active agents, particularly nonionic surfactants;biocides; plasticizers; anti-migration aids; coalescents; fillers andextenders such as carbohydrates, clay, silicates and magnesium sulfate;pigments such as titanium dioxide; hydrophobizing agents such asfluorinated compounds, mineral oils and silicone oils; flame retardants;corrosion inhibitors such as thiourea; urea; antifoaming agents;antioxidants; and others.

These binder additives and adjuvants may be used in conventional amountsgenerally not exceeding about 20 wt. % of the binder solids. The amountof curing accelerator in the binder composition is generally betweenabout 0.05% and about 5 wt. %, based on solids.

Final Binder Composition

The binder according to the present invention preferably has a solidscontent of from about 10% to about 40 wt. %. This is often theconcentration range of the binder in storage containers before use. In aform ready for application, the aqueous binder composition preferablyhas a solids content of from about 1% to about 20 wt. %. In order toachieve adequate application properties and, in particular, sprayingproperties, the viscosity of the binder composition may be adjusted.This is accomplished, for instance, by controlling the type andconcentration of binder components in the aqueous binder system.Viscosity may be kept within the desired ranges e.g. by controlling themolecular weight of the polymeric binder component (lower reactiontemperature, stopping the reaction by adding water at an earlierreaction stage, etc.), and by properly adjusting the relative amounts ofthe binder components and water solvent.

Insulation Product

For producing the mineral wool solar collector insulation, theformaldehyde-free aqueous binder composition according to the presentinvention may be applied to the mineral fibers or mineral fiber productsby conventional techniques such as, e.g., air or airless spraying,rotating disc atomization, padding, saturating, roll coating, curtaincoating, beater deposition, or the like.

The mineral fibers may be any of man-made vitreous fibers (MMVF), glassfibers, ceramic fibers, basalt fibers, slag wool, rock wool, stone wooland others. The mineral fiber products include, for instance, woven andnonwoven fabrics, mats, batts, slabs, sheets and other shaped articles.

For the manufacture of solar collector insulation parts, the polymericbinder is normally applied in an amount of from about 0.1% to 10%,preferably from about 0.2% to about 5% by weight, of the bonded mineralwool product on a dry basis. It is also possible to establish aconcentration gradient of binder over the thickness of the mineral woolinsulation such that the binder concentration is lowest in the (hot)upper region next to the absorber whereas it is higher in the lowerregion adjacent to the housing.

In general, the binder composition is applied, normally by spraying,immediately after fiberization of the mineral melt whereupon the coatedmineral wool is cured in a curing oven wherein heated air is passedthrough the mineral wool web to cure the binder. Typically, the curingoven is operated at a temperature of from about 200° C. to about 400° C.Preferably, the curing temperature ranges from about 225° C. to about300° C. Generally, the curing oven residence time is from about 30seconds to about 20 minutes, depending on, for instance, the productdensity.

Besides thermal curing (e.g. using heated air) other curing methods maybe employed, for example curing with microwave or infrared radiation. Ifdesired, the mineral wool web may also be subjected to a shaping processbefore curing.

The bonded mineral wool product emerging from the curing oven in theform of a bat may be cut to a desired format in accordance with thedimensions of the solar collector. The mineral wool insulation accordingto the present invention may, for instance, have the form of a sheet,plate, mat or strip and can be used for insulating the back and/or theside walls of the solar collector housing.

The mineral wool insulation according to the present inventionpreferably has a thermal conductivity of ≦about 0.040 W/mK and a bulkdensity of from about 10 to about 120 kg/m³. The thickness of themineral wool insulation typically is from about 10 to about 80 mm.

In accordance with the present invention it is also possible to producecomposite materials by combining the bonded mineral wool product withsuitable composite layers or laminate layers formed of a heat-resistantmaterial such as metal, glass surfacing mats and other woven ornon-woven materials. In practice, the mineral wool insulation of thesolar collector is often combined with a cover layer of aluminum foil orcoated with a silicate paint.

The mineral wool insulation according to the present invention usuallysustains the high temperatures (up to about 260° C.) that occur duringoperation of the solar collector, particularly during stagnationperiods, without any harmful emissions that could cause undesiredfogging of the transparent cover. The bonded mineral wool insulationusually is also substantially resistant to ageing and exhibits goodmoisture resistance.

Solar Heating Systems

The solar collector of the present invention may be used in solarheating systems which typically comprise the collector; a heat transfercircuit that includes the fluid and the means to circulate it; and astorage system including a heat exchanger (if the fluid circulatingthrough the collector is not the same liquid being used to heat theobject of the system). The system may or may not include secondarydistribution of heat among different storage reservoirs or users of theheat. The system can be used in a variety of ways, including warmingdomestic hot water, heating swimming pools, heating water for a radiatoror floor-coil heating circuit, heating an industrial dryer, or providinginput energy for a cooling system, among others. The heat is normallystored in insulated water storage tanks.

It is noted that while the present invention has been described withreference to exemplary embodiments, it is understood that the words thathave been used are words of description and illustration, rather thanwords of limitation. Changes may be made, within the purview of theappended claims, as presently stated and as amended, without departingfrom the scope and spirit of the present invention in its aspects.Although the invention has been described herein with reference toparticular means, materials and embodiments, the invention is notintended to be limited to the particulars disclosed herein. Instead, theinvention extends to all functionally equivalent structures, methods anduses, such as are within the scope of the appended claims.

The entire disclosures of the provisional patent application Nos.60/859,500, 60/859,524, 60/859,525 and 60/859,526, all filed Nov. 17,2006 are incorporated by reference herein.

1. A solar collector, wherein the collector comprises a mineral woolinsulation based on man-made vitreous fibers (MMVF) which are bonded bya formaldehyde-free polymeric binder system.
 2. The solar collector ofclaim 1, wherein the MMVF comprise one or more fibers selected fromglass wool, glass filaments, ceramic fibers, basalt fibers, slag wool,stone wool and rock wool.
 3. The solar collector of claim 1, wherein theinsulation comprises black mineral wool.
 4. The solar collector of claim1, wherein the formaldehyde-free polymeric binder system comprises awater-soluble reaction product of an alkanolamine with a carboxylicanhydride which is obtainable by reacting at least one alkanolamine withat least one carboxylic anhydride and, optionally, treating the reactionproduct with a base.
 5. The solar collector of claim 1, wherein theformaldehyde-free polymeric binder system comprises: (a) a polyacidcomponent having acid groups, or anhydride or salt derivatives thereof;and (b) a polyhydroxy component having hydroxyl groups; wherein a pH ofthe binder composition is greater than about
 7. 6. The solar collectorof claim 5, wherein the pH of the binder composition is up to about 10.7. The solar collector of claim 5, wherein a ratio of the number ofmolar equivalents of acid groups, or anhydride or salt derivativesthereof, present on the polyacid component to the number of molarequivalents of hydroxyl groups present on the polyhydroxy component isfrom about 0.6:1 to about 1.2:1.
 8. The solar collector of claim 1,wherein the formaldehyde-free polymeric binder system comprises aheat-curable aqueous composition comprising (a) at least onecarboxyl-containing addition copolymer synthesized from from about 50%to about 99.5% by weight of at least one ethylenically unsaturated mono-and/or dicarboxylic acid, from about 0.5% to about 50% by weight of atleast one ethylenically unsaturated compound selected from esters ofethylenically unsaturated monocarboxylic acids and monoesters anddiesters of ethylenically unsaturated dicarboxylic acids with an aminehaving at least one hydroxyl group, (b) up to about 20% by weight of atleast one monomer, (c) at least one β-hydroxyalkylamine of relativelyhigh functionality, and (d) optionally, at least one surfactant.
 9. Thesolar collector of claim 1, wherein the polymeric binder system ispresent in an amount of from about 0.1% to about 10% by weight of thebonded mineral wool insulation in a dry state.
 10. The solar collectorof claim 1, wherein the collector comprises an absorber and a housingand wherein the polymeric binder system is present in a concentrationgradient over a thickness of the mineral wool insulation such that aconcentration of the binder system is lowest in an upper region next tothe absorber and is higher in a lower region adjacent to the housing.11. The solar collector of claim 1, wherein the mineral wool insulationhas a thermal conductivity of ≦about 0.040 W/mK.
 12. The solar collectorof claim 1, wherein the mineral wool insulation has a bulk density offrom about 10 to about 120 kg/m³.
 13. A solar collector, wherein thecollector comprises a mineral wool insulation based on man-made vitreousfibers (MMVF) which comprise one or more fibers selected from glasswool, glass filaments, ceramic fibers, basalt fibers, slag wool, stonewool and rock wool and which are bonded by a formaldehyde-free polymericbinder system which is present in an amount of from about 0.2% to about5% by weight of the bonded mineral wool insulation in a dry state. 14.The solar collector of claim 13, wherein the insulation comprises blackmineral wool.
 15. The solar collector of claim 13, wherein the mineralwool insulation has a thermal conductivity of ≦about 0.040 W/mK and abulk density of from about 10 to about 120 kg/m³.
 16. The solarcollector of claim 13, wherein the formaldehyde-free polymeric bindersystem comprises a water-soluble reaction product of an alkanolaminewith a carboxylic anhydride which is obtainable by reacting at least onealkanolamine with at least one carboxylic anhydride and, optionally,treating the reaction product with a base.
 17. The solar collector ofclaim 13, wherein the formaldehyde-free polymeric binder systemcomprises: (a) a polyacid component having acid groups, or anhydride orsalt derivatives thereof; and (b) a polyhydroxy component havinghydroxyl groups; wherein a pH of the binder composition is from greaterthan about 7 to about
 10. 18. The solar collector of claim 17, wherein aratio of the number of molar equivalents of acid groups, or anhydride orsalt derivatives thereof, present on the polyacid component to thenumber of molar equivalents of hydroxyl groups present on thepolyhydroxy component is from about 0.6:1 to about 1.2:1.
 19. The solarcollector of claim 17, wherein the formaldehyde-free polymeric bindersystem comprises a heat-curable aqueous composition comprising (a) atleast one carboxyl-containing addition copolymer synthesized from fromabout 50% to about 99.5% by weight of at least one ethylenicallyunsaturated mono- and/or dicarboxylic acid, from about 0.5% to about 50%by weight of at least one ethylenically unsaturated compound selectedfrom esters of ethylenically unsaturated monocarboxylic acids andmonoesters and diesters of ethylenically unsaturated dicarboxylic acidswith an amine having at least one hydroxyl group, (b) up to about 20% byweight of at least one monomer, (c) at least one β-hydroxyalkylamine ofrelatively high functionality, and (d) optionally, at least onesurfactant.
 20. A solar heating system, wherein the system comprises thesolar collector of claim 1.